Hikaru vs MagnusCarlsen: game review

21.O-O! The only good move here: every alternative is clearly worse.

• Castles: the king gets out of the centre and the rook joins the game.
• Connects the rooks: development is complete and they can now support each other.
• The next best move, 21.O-O-O, would drop White's winning chances from 64% to 52% (+0.20).
• 21.O-O stops …Qxg3+.
• Black was threatening …Qxg3+, winning a pawn. O-O takes care of it.
• Black answers 21…O-O, winning a pawn.

22.b4 is a mistake: White's winning chances go from 65% to 51%.

• Black answers 22…Bxf3, which takes the knight on f3.
• After Bxf3, Black wins 1 point of material within 4 moves.
• Better was 22.Kh2 (+1.72), which protects the g3 pawn, which was hanging.

Better: 22.Kh2 protects the g3 pawn. Engine line: 22…Bxf3 23.Nxf3 Nxc4 24.Rad1 Qc5 25.Qxe6+ Kh8 (+1.72).

26…Nxe5! The only good move here: every alternative is clearly worse.

• Takes the knight on e5.
• Protects the queen on c6, which was hanging.
• The next best move, 26…Qe6, would drop Black's winning chances from 50% to 34% (+1.76).
• 26…Nxe5 stops Nxc6.
• White was threatening Nxc6, winning the queen for a knight. Nxe5 takes care of it.
• Trades knights.

34…Kg8 is a blunder: Black's winning chances go from 48% to 4%.

• White answers 35.Re8+: the rook joins the attack: it now hits 2 squares around the Black king.
• Better was 34…Qd1 (+0.21): shores up the h5 pawn, which was under as much attack as it had defence (1 against 1).

Better: 34…Qd1 stops Rxh5+. Engine line: 35.Rg5 Rb6 36.Rd5 Qg4 37.Qe3 Rc6 (+0.21).

• Both sides followed opening theory up to 7.Nxd4: 13 moves in all, 7 by White and 6 by Black.
• Theory runs out after 7.Nxd4: too few games between strong players reached this position to go further.